In recent years bicycling has become a very popular recreational and physical-conditioning activity. Many recreational bicycle riders equip their bicycles with one or more carrier bags to carry clothing, food, camera equipment, first aid kits, tools and other articles that they may need or wish to use in the course of a ride. A particularly popular type of bicycle carrier bag is a handlebar bag, and numerous designs for bicycle handlebar bags have been proposed and commercialized over the years.
Experienced bicycle riders know that one of the most important attributes of a bicycle carrier bag, including handlebar bags, is the ability to resist motion relative to the bicycle, particularly side-to-side motion. Side sway of a handlebar bag significantly increases the amount of effort required to steer the bicycle, particularly when the rider is peddling hard, and also increases the effort required to maintain balance because of the increased lateral acceleration caused by the shifting load.
There have been various proposals for stabilizing bicycle handlebar bags. One example is found in U.S. Pat. No. 4,066,196 (Jan. 3, 1978), which describes and shows a handlebar bag supported from the top by a bent wire carrier that hooks under the stem and over the handlebars and has spaced-apart forwardly extending arms received in sleeves at the upper edges of each of the bag side walls. The wire carrier provides reasonably good stability for the upper part of the bag. In an effort to stabilize the lower part of the bag against side sway, elastic cords are connected to each side of the bottom of the bag and extend down to lower attachment points close to the wheel dropouts of the front fork. The elastic cords impart a degree of stability to the lower part of the bag, but because they are inherently elastic, they merely reduce but do not eliminate side sway of the lower part of the bag.
In a relatively recent design for a handlebar carrier bag found in U.S. Pat. No. 4,542,839 (Sept. 24, 1985), a flexible fabric bag is partially stabilized as to shape and load-carrying ability by a substantially rigid plate that is co-extensive with the back wall of the bag and by a U-shaped rod member hinged in an inverted position to the lower edge of the back plate and positioned with its legs extending diagonally along the side walls to locate the base of the U along the upper edge of the front wall of the bag. U.S. Pat. No. 4,542,839 further proposes a bent wire carrier member that hooks under the stem and over the handlebars very much like the arrangement of U.S. Pat. No. 4,066,196. A mounting assembly comprising one component attached to the back plate of the bag and another component attached to or part of the wire carrier affixes the bag on the handlebars. One element of the attachment system is an elastic cord for inhibiting vertical motion of the wire carrier.
The carrier bag and mounting system of the '839 patent provides reasonably good support for the upper part of the bag by virtue of stabilization of the upper edges of the front and rear walls. In addition, the lower edge of the rear wall of the bag is stabilized by the back plate. Nonetheless, a large part of the lower portion of the bag is not restrained against lateral movement. Inasmuch as the lower part of a bicycle carrier bag is often loaded with the heaviest articles, there is a particular need for stabilization of the lower portion of the bag against side sway, a need that is not fulfilled by the designs of either the '196 or '839 patents.
It is known from U.S. Pat. No. 4,271,996 (June 9, 1981), which is assigned to Cannondale Corporation, the assignee of the present invention, as well as the successful commercialization of the invention of that patent, to stabilize a flexible bicycle bag by means of a substantially rigid three-dimensional frame comprising a back portion and a top portion and side members joined between the top portion and the back portion in the upper part of each side of the bag to stiffen and shape the upper part of the bag so that loads carried in the bag are supported from the top and the bag is prevented from sagging. If one were to consider the three-dimensional frame of the '996 patent for use on a handlebar bag, the result would be much the same as the result of the designs in the '839 and '196 patents, namely good support for and stabilization in the upper portion of the bag but little stabilization against side-sway in the lower part of the bag.